Martyrius is the author of a work known as De b muta et v vocali. In addition to being transmitted independently by a few codices, this work was epitomized by Cassiodorus and subsumed - in reduced form - within his De orthographia. Since we know the latter work was composed in 580 AD, we may safely conclude that De b muta et v vocali must have been composed before that date. After an introduction boasting that earlier grammarians had never treated the difference between b muta and v vocalis, Martyrius explains the use of each in initial, central, and final syllables of both nouns and verbs. Consulting Greek grammatical treatises enabled Martyrius to provide information on the Greek language and even the text of Homer. It is possible to recognize the influence of the scholastic-grammatical tradition within the work, and the regulae used for explanation are enriched with onomastic elements that are useful for identifying the differentiae verborum (Pugliarello). [A. Balbo–S. Mollea; tr. C. L. Caterine].